Belisarius has a fictional universe written around him being the Greatest Ever, so that seems a pretty strong indication. According to Wikipedia, he was successful despite being actively worked against by his OWN EMPEROR, and increased the size of the Western Roman Empire by about 45%. Plus, Wikipedia is pretty sure he had an epic chin.

Caesar is known for, what? The Gaul? Then he went even more into politics and ended up running Rome? Alexander's empire, despite extending well into Asia, ultimately didn't matter. Hannibal basically did something very, very stupid and got away with it.

Scipio defeated Hannibal and Carthage, was loved by the Roman people, and was driven out of Rome after false charges by his peers.